The overall objective of this research is to study the effects of halothane and other selected volatile anesthetics on the structure and function of microfilaments measuring 40-80A in diameter which have been shown to be responsible for a variety of biomotion phenomena in a wide range of cell types. Various cell types including explanted sympathetic neurons, neurons and glia dissociated from brains, glioblastoma cells, and cardiac and smooth muscle cells, will be studied for any effects of halothane on motility and morphological differentiation for comparison with data already obtained from cultured neuroblastoma cells. Cultures will be exposed to volatile anesthetics in a stage mounted tissue chamber incubator and monitored by light microscopy. Electron microscopy will be employed to determine an ultrastructural basis for any observed inhibition of motility or morphological differentiation. Model studies with purified actin solutions will be used to determine whether halothane can affect actin filament structure and function directly by interacting with the actin protein or indirectly by modifying the filament environment. Synaptosomal preparations will be investigated by electron microscopy for the presence of actinoid and myosinoid components and their possible alterations by volatile anesthetics. Ultrastructural studies on various regions of intact brain tissue from rats anesthetized with halothane will emphasize possible reversible structural changes associated with anesthesia in vivo.